1. Field of the Invention
The present invention relates to a washing machine and a method of controlling the same, and, more particularly, to a washing machine and a method of controlling the same that is capable of determining whether laundry is a single load or a multiple load based on detected value of eccentricity or detected laundry amount and changing revolutions per minute of a motor or the number of eccentricity detections based on the determined load amount such that different spin-drying actions are performed, thereby preventing incorrect determination as to whether the laundry is a single load or a multiple load and malfunction of the washing machine and reducing time required until a spin-drying entry is initiated.
2. Description of the Related Art
Generally, a washing machine is a machine that washes laundry to removes contaminants from the laundry. According to a selected washing operation, wash water is supplied into the washing machine such that the laundry is sufficiently submerged in the wash water, an appropriate amount of detergent is dissolved in the wash water such that the contaminants are removed from the laundry by a chemical action between the contaminants and the dissolved detergent, and a drum, in which the laundry is received, is rotated such that the contaminants are removed from the laundry by mechanical friction between the laundry and the wash water.
FIG. 1 is a perspective view showing the structure of a conventional washing machine 1. As shown in FIG. 1, the conventional washing machine 1 comprises: a drum (not shown) for receiving laundry; a motor (not shown) for rotating the drum; an input unit (not shown) for inputting information to set the operation of the washing machine 1; a display unit (not shown) for displaying the operation of the washing machine 1; and a microprocessor (not shown) for controlling the washing operation of the washing machine 1 and all the other operations of the washing machine 1.
The conventional washing machine 1 further comprises: a water supply valve and a water drain valve, which are turned on and off. The washing machine 1 performs the washing operation of washing the laundry received in the drum under the control of the microprocessor.
After the washing machine 1 removes contaminants from the laundry, the motor is driven at high speed such that moisture is removed from the laundry by centrifugal force generated in the drum. In this way, the spin-drying action is performed by the washing machine 1, by which the laundry can be easily dried.
Now, a method of controlling the conventional washing machine with the above-stated construction will be described with reference to FIGS. 2 and 3. FIG. 2 is a flow chart illustrating a load determining process of the conventional washing machine, and FIG. 3 is a flow chart illustrating a spin-drying entry process of the conventional washing machine in the case of a single load.
According to a washing course set by a user, the washing machine 1 performs a washing/rinsing/spin-drying operation, and therefore, a water supplying action and a water draining action are repeatedly carried out (S1).
While each of the above-described operations is performed, a spin-drying action is performed several times. Before the spin-drying action is performed, an eccentricity detecting process is performed to determine the degree of eccentricity of laundry received in the drum. The eccentricity detecting process is repeatedly performed a predetermined number of times or more (S2).
At this time, detected value of eccentricity is counted whenever the detected value of eccentricity is equal to or greater than a predetermined reference value of eccentricity. When the counted number of the detected value of eccentricity equal to or greater than the predetermined reference value of eccentricity is a predetermined value or more, the washing machine 1 determines that the laundry is a single load. When the detected value of eccentricity is equal to or greater than the predetermined reference value of eccentricity, or the counted number of the detected value of eccentricity equal to or greater than the predetermined reference value of eccentricity is a predetermined value or more, on the other hand, the washing machine 1 determines that the laundry is a multiple load (S4, S6).
Especially when the counted number of the detected value of eccentricity equal to or greater than the predetermined reference value of eccentricity is 19 or more after the eccentricity detecting process is performed 20 times or more, the washing machine 1 determines that the laundry is a single load.
Based on the determination as to whether the laundry is a single load or a multiple load, which is performed by the eccentricity detecting process, revolutions per minute of the drum is changed, and then the spin-drying action is carried out (S5, S7).
The spin-drying entry process of the conventional washing machine in the case of a single load is performed as follows.
As illustrated in FIG. 3, it is determined whether the load received in the drum of the washing machine is a single load or a multiple load through the above-described procedure after water is drained (S11, S12).
When it is determined that the laundry is a single load, a value of eccentricity of the laundry is detected before the spin-drying action is carried out.
At this time, the detected value of the eccentricity is compared with the predetermined reference value of eccentricity to determine whether the detected value of the eccentricity is equal to or less than the predetermined reference value of eccentricity (S13).
When the detected value of the eccentricity is greater than the predetermined reference value of eccentricity, the eccentricity of the laundry is detected several times until the detected value of the eccentricity is equal to or less than the predetermined reference value of eccentricity. When the detected value of the eccentricity is equal to or less than the predetermined reference value of eccentricity, on the other hand, the spin-drying action is carried out (S14).
If the detected value of the eccentricity is greater than the predetermined reference value of eccentricity for a single load, the washing machine 1 repeatedly performs the eccentricity detecting process. When the above-described spin-drying entry attempt is performed 35 times or more, the rinsing action is carried out again.
If the spin-drying entry attempt, at which the eccentricity detecting process is repeatedly performed until the detected value of the eccentricity is equal to or less than the predetermined reference value of eccentricity, is performed 70 times or more, it is determined that the washing machine has malfunctioned, and therefore, the operation of the washing machine is stopped.
In the load determination process of the conventional washing machine 1, however, the spin-drying action is carried out based on the initial determination as to whether the laundry is a single load, and the determination as to whether the laundry is a single load or a multiple load is repeatedly carried out when the spin-drying entry is initiated while the washing/rinsing operation is performed. As a result, it takes too much time until the spin-drying entry is initiated. Consequently, washing time is increased, and therefore, energy efficiency is reduced.
Large-sized towels or winter clothes are laundry the amount of which is large. In the load determination process of the conventional washing machine 1, however, such laundry, the amount of which is large, is determined to be a single load, and therefore, the spin-drying action is carried out based on the single load.
As described above, a large amount of laundry is determined to be a single load, and therefore, the spin-drying action is carried out based on the single load although the value of eccentricity is large. As a result, excessive vibration or noise is generated from the washing machine. Furthermore, the washing machine may overheat.
In addition, the spin-drying entry process of the washing machine 1 has the following problems. When the washing machine 1 is operated while one or two pieces of laundry are received in the drum, the laundry is determined to be a single load, and therefore, the value of eccentricity of the laundry in the drum is greatly increased. As a result, the eccentricity detecting process is repeatedly performed for several minutes until the value of eccentricity is equal to or less than the predetermined reference value of eccentricity. Consequently, time required until the spin-drying action is carried out is increased. Furthermore, when the operation of the washing machine 1 is stopped due to several spin-drying entry attempts, it may be incorrectly determined that the washing machine 1 malfunctions.